017688840097 is this a genuine O2 customer service number?

Not o2 customer service, it is a number that belongs to o2 and is used by external callcentres.

Thanks. I am getting calls from this number every day, several times. Due to work, I could not receive the call . When I call them back and ask for an English speaker, they say they will call me back later. Somehow, I miss that again. And this annoying cycle continues. I do not even know what they want from me or what their offer is. Are they authorized or is it a scam? 

Just block the number in your phone. It will not be anything important. You can also opt out of receiving such telephone calls by changing your settings in the customer portal.

Hello ​@Faruq2025 welcome at our Community.

I'm sorry you get these calls so often. Yes, the number is ours. Unfortunately, I don't know exactly what it's about. But I can put a note saying you don't want to be called again.

If anything happens, we're always here to help. Just write to us. 😊

Kind regards, Ines.